mitchell



2 Sheets-Sheet 1 E. MITCHELL EXTRUSION OF METALS Filed Aug. 8, 1927 Aug.28, 1928.

Aug. 28, 1928. 1,682,399

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UNITED STATES PATENT OFFICE.

EXTRUSION OF METALS.

Application filed August 8, 1927, Serial No. 211,547, and in GreatBritain September 23, 1926.

This invention relates to the extrusion of metals, as for example,magnesium or magnesium alloys, and has for its object the production byextrusion of articles having a central boss and radiating arms, such asacroplane propellers. not hitherto produced by such process. Theinvention relates more particularly to the known method in which themetal is caused to extrude in a lateral direction relatively to thedirection of application of the pressure setting up extrusion.

The invent-ion consists in the extrusion of articles comprising acentral boss and radiating arms, themetal being forced into a pair ofsimilar matrices or die parts which, when assembled, provide a centralaperture for the formation of the boss and radial or lateral passagesthrough which the metal is extruded into the atmosphere and which givethe requisite shape to a portion of the length of each arm adjacent tothe boss.

In one convenient application of the invention to the production ofaeroplane or like propellers, or other articles having a central bosslike part with blades, arms or projections radiating or projectingtherefrom, the metal or alloy at the required temperature 's forced, bya hydraulic ram or otherwise, from a container into a die disposed atone end of such container or cylinder.

The said die is made up from a pair of similar matrices or die partswhich, when assembled, provide a central aperture for the formation ofthe boss of the propeller or other article and radial or lateralapertures such that the metal can flow or extrude therethrough from suchcentral aperture to the exterior of the die. The said lateral aperturesare of such form or section as to give the required shape to a portionof the blades or like parts of the propeller or other article adjacentto the central boss.

The charge of metal forced from the cylinder or container into the saiddie is sufficient to produce the boss of the article and also by theflow or extrusion of the metal throughthe said lateral apertures toprovide blades or arms radiating or projecting to the required extentfrom such boss and from the die.

Referring to the accompanying explana tory drawings Figure 1 1s asectional elevation and Figure 2 a sectional end view illustrating, 1ndiagrammatic form, one manner of producing an aeroplane propeller inaccordance with this invention.

Figure 3 is a sectional plan illustrating another manner of applying theinvention, in the production, for example, of the arms or spokes of awheel integrally with the boss or centre of the wheel.

Figures 4, 5, 6, 7 and 8 are cross sectional views on the lines 44, 55,66, 7-7 and 88 of Figure 2, showing the cross section of the radialpassages through which extrusion is effected.

The same reference letters and figures in the different views indicatethe same. or similar parts.

Referring to Figures 1, 2, 4, 5, 6, 7 and 8, the four blades or arms ofthe propeller and the boss or centre are formed with the aid of a diepart a having a central matrix 5 for the formation of the boss and thematrices c radiating therefrom for the formation of the root and aportion of each blade or arm, the said matrices 0 being of the re uiredcross section, which may vary in diderent parts, to produce bladeportions of the re quired shape. Figures 4 to 8 show the cross sectionsof the blades at various points in the die. The blades project beyondthe outer ends of the said matrices c and are subsequently finished bymachining operations. The die is suitably split or divided or made ofsegmental form to permit of separation for the removal of the propeller.

The container or cylinder all into which the metal is inserted forextrusion, has one end abutting against the face of the die a as shownat Figure 2. The extrusion pressure is applied, by a ram or otherwise,in the direction indicated by the arrow 1 (Figure 2) and under suchpressure the metal is forced into the die and extruded from the centralmatrix 6 towards the outer ends of the matrices 0, as indicated by thearrows 2, for the formation of the propeller.

In the example illustrated at Figure 3, of the manner of producinghollow wheel arms or spokes integrally with a'wheel boss or centre, thecontainer or extrusion cylinder d is in two parts with the die ainterposed between them. The extrusion pressure is applied to eachcylinder part as indicated by the arrows 1, and to give the hollowformation to the Wheel arms or spokes a fixed mandrel or core as e isdisposed as shown in the centre of each of the matrices c which radiatefrom the central matrix I).

What I claim is 1. Means for the extrusion of metals to form articleshaving a central boss and arms radiatin" from said boss, consisting inpart of a die Iiaving a central matrix for the formation of the saidboss and a plurality of matrices radiating from saidcentral matrix andextending to the perimeter of thedie into and from which the metal isextruded for the formation of the said arms;

2. In means for the extrusion of metals to form articles having acentralbossfand arms radiating therefrom, the combination c0111- prisinadie having a central matrix and a plurality of lateral matrices open attheir outer ends radiating from said central matrix and extending to theperimeter of the (lie,

lateral matrices radiating therefrom and shaped to correspond with theroot and a portion only of the length of each blade, the end of eachlateral matrix being open so that the metal issues into the atmospherefrom the die, a container for metal at right angles to the radiatingmatrices, and means extruding the metal from the container into the dieand partly into the atmosphere through the die.

In testimony whereof I have" signed my name to this specification.

ERNEST MITCHELL.

